Aeroplane flight control



July 10, 1,934- J; M. HENDRlcKsoN Re. 19,233 l 'AEROPLANE FLIGHT cdN'rRoL ',onginal Filed man 6. 1931 :s snelsnez 1 July 10, 1934- J. M. HENDRlcKsoN l19,233 i AEROPLANE FLIGHT CONTROL Original Filed latch 6. 1931 3 Sheets-Sheet 2 4 Javento! zu, fw )hm July l0, 1934. J. M. HENDRlcKsoN `R- 19,233

` AEROPLNE FLIGHT CONTROL Original` Filed Ilarch 6, 1931 :s sheets-sheet 3 ffr/ tx'g.

f innesca division February zs, 1933, serial No.

Reinued July l0, 1934 y Re. A19,233

UNITED STATES PATENT-OFFICE AEBOPLANEFLIGHTCQNTROL Jameslll. Hendrickson, Mcxeesport, Pa.

Griginal No. 1,866,596, dated July 12, 1932. Serial No. 520,731, March 6, 1931. Application forressaooz 9 claims. (ci. zii- 29) Among the objects which I have in view is the matically return the airship to andmaintain it provision of a new and improved electrically operin its normal level iiying position ating control which is connected up with the Fig. 7isadiagrammatic view showingthecomailerons and/or the elevators whereby lateral `inatifm with the arrangement shown in Fis. 6 5. and/or longitudine; tipping is eutometieaiiy cerof means for righting an inverted aeroplane. no

rected and the aeroplane maintained level in nor- F18- 7G 1S a detail in enlarged section illustratmai flight, f ing the preferred arrangement o! the control For this' purpose I have invented a new and Switch improved control tube which tips or loses its level Fig. 8 is an enlarged vertical section of the verl position with the plane and which when tipped tical contl'iltllllet 65 establishes electrical circuits through soienoids Fis- 9 isa plan view showing the principles 0f which are connected up to operate the ailerons my invention embodied in an arrangement for end/or the elevatore, use inconnection with a radio frequencyaltlm- I also have invented en improvement in the ,eter i'or maintaining the `aeroplane in night at i solenoids employed -to operate the ailerons and/or e Conste-llt predetermined heiht BbOVe the 7J the elevators, the same being divided into sections 8l`0lllldso that the proper connection will beprovided Fig. 10 is a side elevation of the same showing dependent upon the amounto! digression i'rom l illtimetel' and Some 0f the Wirin8` beine Omit'- normal-night` Again I provide means for automaticauy right- Referring ilrst to Fies- 1 te 5 inclusive. 1 renis' ing an aeroplane which has become inverted in resents a tube formed of suitable non-conductmghfh ing material: In Fig. 1 I have indicated the tube Again I have applied the principles or my inas formed 0f transparent material such as glass.- vention to use in connection with a`radio or other but in 'Practice B less fragile material, Such 8S altimeter whereby the aeroplane will be autobakelite, i8 Preferilble- The ende 0f the tube are C y matically maintained at a predetermined eleva- Sealed 8S by the Cells 2 ands Whichlllnybe Serewed tion of flight, onto the ends oi' the tube.

My improved control tube or electric switch is 'I'he tube is mounted on the aeroplane in such adaptable for use generally in connection with mnnel' 8S t0 be herizvntal when the aerOnlne electric circuits. 1S in 110111131 level lht- 85 Other novel features of construction, 'and' also M0118' its t0n center line and adjacent t0 either 0f arrangement 0f pai-ts wil] appenpfrom the folend 0f the tube the Wall 01' the latter ls provided lowing description with a series oi' spaced apart holes through which In the accompanying drewings wherein I have the contact posts 4 are downwardly inserted. 'Ihe 5 illustrated the practical embodiments ofthe prinhUleS and the posts are threaded to secure the go ciples'of my invention, Fig. 1 is a diagrammatic POStS in POSitiOn' and also' t0 permit an adjustview showing one or my improved stabilizer tubes ment of the protrusion of the posts into the inconnected up with a pair of oppositely disposed .terior of the tube, thus adjusting the sensitivity solenoids and arranged i'orautomatlcally operat- 0i' the stabilizer. 43 ing either the ailerons or elevators of an aero- In the lower portion oi' the tube is contained a g5 plane. Y body 5 of liquid whichis a good conductor of elec- Fig. 2 is a similar viewbut incomplete showing tricity. such as mercury. The top level of the the tube tipped and one of the sections of one of liquid 5, when the tube is horizontal. is below the 4the solenoidenergized. lower lextremities of the posts 4. 'I'he posts are 45 Pig. 3 is a broken longitudinal section on enadiustedrelative to the t0n level 0f the'mercury 10o larged scale of the tube, the conductive liquid to obtain the sensitivity desired in the Operation and the non-electrolytic uid' being shown only oi' the control tube. Above the'level of the mer. at one end. cury is a Vbody 6 oi' nonrel'ectrolytic fluid. prefer- Fig."4 is a cross section of the tube taken along ably a liquid oi' low viscosity, such, for instance, the lined-4 inFig. 3. as carbon tetra-chloride. 'Ihe posts must be of 105 Fig. 5 is a broken perspective of the sui-gea material which will not alloy with the mercury or preventer. other huid. Fig. 6 is a diagrammatic view showing a pair When thetube is horizontal the lower ends of oi my improved stabilizer tubes arranged Aior the the posts are immersed in the liquid 6 and such control o t the ailerons and the elevators to itutoliquid lies between the extremities of the posts 110 .mercury or other nately bent upwardly and downwardly to form the ns 8 and 9, respectively, which iins are immersed'in the mercury and prevent the mercury from surging as the tube is tipped. One end of the bar '7 is provided with a threaded contact post f sertion into a slot 12 formed in 10 which extends through a snugly fitting cylindrical neck 1l in the cap 2. The other orr inner end of the bar 'l isl suitably suported as by in' theinner end of a cylindrical boss 13 of the cap 3. The slot l2 may be annular in form so that aportion thereof will always be properly disposed to receive the inner end of the bar '1. The surge-preventer acts y as a conductor ot the electric current.

- of the' two solenoids whi1e vto ` divided and likewise inly positioned binding post.

. horizontal position .trois are not activated.

'the circuit which 14 and 15 represent a pair of solenoids oppositely-disposed and 'having their cores i6 connected as by links 1'1 to a pivoted lever 18 which .is coupled as by links 19 to the controls, such as y the ailerons or the elevators of the aeroplane. 20 represents the source of electric current, preferably a dynamo which may be driven by the aeroplane motor. l

One side of the dynamo 20 is connected by the branched wire 21 with the front ends of the coils the other side of the dynamo is connected by the wire 22 with the binding post 10. The ground circuit is provided with a switch 23 convenient to the handof the operator of the aeroplane. The switch is arranged so that the entire control circuit may be thrown into or out of operation at the will of the operator. The coils of the solenoids are preferably divided into sections as shown, the number of sections being equal to the number of binding posts 4 at each end of the tube 1. Thus I have shown three binding posts at each end of the tube and the coils each divided into three sections.` The number of sections into which the solenoids are the number of binding posts 4 depends upon the sensitivity desired for the control. are connected by a wire 24 with the correspondthe tube 1 in a as it is when the aeroplane is in normal level night. the posts 4 are all out of contact with the mercury in the tube and thus the circuit which includes the and the solenoids are disenergized and the conbut when the tube tips, as it does as the aeroplane assumes a non-level posi-v tion, the mercury will rise at the lower end of the tube. as indicated by the line ain Fig. 2.`thus With the switch 23 closed and bringing it into contact with the lst binding p08?,

4 at the left end lof the tube and thus completing coil of the solenoid 14 and causing'the Vlever 18 to be swung .ounterclockwise, thereby shifting the ailerons or the elevators, as the case may be, to restore the aeroplane to normaliiying position. Incase the angle of the tip is sufficiently great the next or-the remaining posts'at the end of the tube will be brought into electrical contact with the mercury. thus energizing the next or the resections of the solenoid coil and thus setting the controls at a greater angle of comreventer for this mercury.-

uid, such as steel or iron. At` -,intervals the material of the bar is cut and alter- .mal nying position,

The outer ends of each of such sectionsdynamo Ais broken includes vthe nrst section of the wardly and this pensation to bring the aeroplane'back to normal through a greater arc.

I In practice I make the iirst sections of the solenoid coils of suillcient strength to move the con trols against maximum resistance. The other sections are supplementary to increase the angles of control movement.

When the aeroplane is brought back into northe contact between the posts and the mercury is interrupted by the leveling of the tube, the solenoid is disenergized and the controls return to normal.

Insomuch as mercury and similar conductive liquids are unstable,it is necessary to prevent the surging of the liquid, since otherwise intermittent contacts with the posts might ensue, confusing and impairing the operation of the automatic control. `I'arri. able by means of my surgepreventer to render the mercury stable. Again the use of the surge-preventer as a conductor of the current provides a route of less resistance through the mercury to the points of contact and lessens the resistance of the travel of the current through the mercury'when contact is made.

The non-electrolytic fluid prevents the oxidization of the mercury which would render it too sluggish and also prevents the vaporization of the mercury due to spark gaps which would re-l sult in arcs.

The non-electrolytic substanceishould have no chemical reaction with the conductive liquid and I Thus one er the tubes, indicated et m, is posi- Y tioned transversely of tliieaeroplane so as to be responsive to llateral tipping of the latter, and the posts 4 of said tube areconnected to the opposed solenoids 14a and 15a whose cores are linked to the lever 18a which is connected up to the ailerons. Again a second stabilizer tube, indicated at lb, is disposed longitudinally of the aeroplane, so as to be responsive to the ascent or descent of the latter. The posts 4 vat the opposite end of the tube 1b are connected up, respectively, to the coils of the opposed solenoids 14h and 15b which are linked to the lever 18h which in turn is connected to the elevators of the aeroplane.

The lead 21a from one side of the dynamo 20 is connected to all the solenoid coils. while the opposite lead 22Go! the dynamo is connected to the posts 10 of the two tubes 1a and 1b. l 23 represents the control switch placed convenient to the hand of the operator.

The preferred arrangement of this switch is illustrated in Fig. 7a, the electrical connection between the portions of the lead 22a being normally maintained by the disk 23a which is spring pressed in place. The switch is mounted on' the control stick 23h within reach-of the operators hand. When the operator wishes to put the vautomatic control out of operation, as when landing or taking otl'. he presses the button 23e downinrrupts the lead 22a. If he loses consciousness the switch automatically closes and puts the control into operation. y

It is obvious that the aeroplane would be automatically returned 'to normal ying position when a deviation therefrom occurs. In taking ofi' and in landing the switch 23 is thrown open.

In Fig. 7 I have shown the control illustrated in Fig. 6, arranged to automatically l'lsht an aeroplane which -is traveling in an inverted or upset state.. In this casethe branchedlead 21a is connected to the solenoids 14a and 14h which are arranged to activate the left aileron and the up-elevators, while the solenoids .15a and 15b which activate the right aileron and the downelevators are connected to a branch conductor 2lb leading from the lead 21a and in which control tube 24 is interposed.

The tube 24, which is shown in detail in Fig. 8, is vertically disposed while the aeroplane is in normal flight. 'I'he tube comprises a cylindrical portion formed of bakelite or some other suitable non-conductive material, which is mounted in a base 25 which may be secured to a portion of thev is closed by a cap fuselage. 'I'he top of the tube 26.

27 represents a body of conductive liquid, suc'h as mercury, which when the aeroplane is right side up occupies the` lower portion of the tube and forms anelectric connection between the two opposed binding posts 28 and 29 which extend through the wall oi' the tube adjacent to its lower end. These posts are connected to the ends of the conductor 2lb at `the interruption in the latter asillustrated in Fig. 7.

Inthetube 24abovethemercuryisabody .of non-electrolytic iluid 30.

The cap 28, which may be of non-conductive material, is provided with a binding post 31 which extends through the side wall of the cap and said post 3l is connected by a branch conductor 22h with the lead 22a. 32a represents wires connected to the sections of the solenoid 14a and 32h represents wires connected to the sections of the solenoid 14h and 'these two groups ,of wires areled into the interior of the tube 24 at different points through holes in the side wall oi' the cap 26, the" said groups being normally insulated from each other and from the binding post 31. When the aeroplane is inverted and the tube 24 is likewise inverted, the mercury ilows to the opposite end of the tube 24, thus interrupting the continuity oi' the conductor 2lb and breaking the electrical connections between the solenoids 15a and 15b and the dynamo, thereby preventing the right aileron from being thrown to raise the right wing of the plane and also preventing the elevators from being set to direct the plane upwardly.

matically vmaintaining an aeroplane at a predetermined elevation. above the ground. 'l'his arrangement is illustrated in Figs. 9 and 10 of the drawings.

'Ihe radio frequency altimeter is not per se the subject matter of the present invention, and therefore I have simply indicated it generally in the drawings instead of illustrating and describing its construction in detail. It is suillcient for the present purposes to state that-it comprises a plurality of signals, usually incandescent lamps, which indicate elevations. In the present practice the operator of the aeroplane notes such signals and operates his controls when necessary to correct faults in elevation. "Therefore as now employed, the effectiveness and the usefulness of the radio altimeter is limited by the necessity of the conscious cooperation of the operator.

The radio mmmis indicated at 33 and it.

is shown provided with three signal lamps 34a., 34h and 34e. The lamp 34a, usually green, is illuminated when the aeroplane is at or above the predetermined elevation above the ground, for example at an elevation of one thousand feet; the lamp 34h, usually showing yellow, is illuminated when the plane descends below the predetermined elevation. say one thousand feet, but before it descends to what may be regarded as a dangerously low elevation, say five hundredfet, while the lamp 34e. usually showing' red,is illuminated when the' aeroplane descends below nve hundred feet.

In Figs. 9 and 10.1 show the aileron control tube la and the elevator control tube 1b mounted on a plate 35 which is hinged at one end, as at 36, to a platform 37 which is part of the body of the fuselage of the aeroplane and which is horizontal when the aeroplane is in normal level ilight.

4The axis of movement of the plate 35 relative to the platform 37 is at right angles to the longi tudinal axis of the elevator control tube 1b so that when the plate 35 is raised relative to the platform the tube lb will be ytipped in such manner as to shiittheelevators so/ that the aeroplane will ascend and thus correct/the elevation.

The platform 37 is provided' with an upwardly extending bracket 38 which supports from above the vertically disposed solenoid 39 whose core is connected bythe depending link 40 to the free end of the plate 35, so that when the solenoid is energized, the free end of .the plate 35 will be raised, the control tube 1b will be tipped and the elevators shifted to cause the plane to ascend.

The front or lower end lof the coil of the solenoid 39 is connected to the conductor 41 which is connected to the dynamp through the lead 21a. 'I'he coil is also divided into two sections, the rear ends of which are'connected by the wires 42 and 43 to the conductors of the lights 34h and 34e, the wire 42 of the front or lower section'being connected up with light 34h and the wire 43 of the rear or upper section being connected up to the light 34e. 'Ihe altimeter is connected to the dynamo by the conductor 44 which is a branch of the lead 22a.

Thus when the light 34a is illuminated, the

vcircuit oi solenoid 39 is incomplete .and the solenoid is not energized. When the yellow light 34h is illuminated the circuit is completed through the wire 42', energizing the lower lsection of the c oil ofthe solenoid 3,9 and tilting the plate 35 and thereby causing the elevators to be shifted so as to cause the'aeroplaneto ascend. In case the drop of the aeroplane is so-extensive as to i1- luminate the red light 34e, the circuit is interrupted through the wire 42 and is established through the wire 43, thus energizing the full length of the solenoid coil, causing a maximum tilt of the plate 35and thereby causing the elevators to be swung into their maximum ascending position.

When the plane assumes the angle of climb determined by the'tilt of the ,elevators the tube lb in normal night; whereby they are maintained tending into said at any predetermined elevation, and whereby an aeroplane inverted inv night is automatically -righted.

What I claim iszl. In an aeroplane, a control system including solenoids arranged to activate the controls of the aeroplane, a make and break device comprising a tube ,of non-conductive material, contact members extending into the tube adjacent the ends thereof and connected to the coils of the solenoids, a body of conductive liquid contained in said tube, the liquid being out of contact with said contact members when the tube is level, and a conductor member extending longitudinally of the tube and normally immersed in said conduc.

tive liquid, said conductor being connected to a source of electrical current, means carried by the conductor to prevent surging of the liquid resulting from the movement of the tube, whereby when the tube is tipped electrical contact is made between one o f the members and the conductive liquid and the corresponding solenoid. is energized.

2. In an aeroplane, a control system including solenoids arranged to activate the ailerons and elevators of the aeroplane, a make and break Adevice normally interposed inthe circuit of one of the aileron-control solenoids and the circuit ofthe down-elevator-control solenoid, and arranged when the aeroplane is inverted to open said circuits and to complete the circuits of the other aileron-control solenoid and of the up-elevator-control solenoid, whereby the inverted aeroplane is caused to lright itself in night. Y

, 3. In an aeroplane, a control system includin solenoids arranged to activate the controls of the aeroplane, a make and break device comprising a tube of insulating material arranged to be mounted on the aeroplane and disposed in a ver-e. tical position when the plane is in normal night, 1

a body of conductive liquid partially nlling said tube, a pair of contact members extending into said tube and interposed in the circuit of one of the aileron-control solenoids and of the downelevator-control solenoid, and contact members extending into said tube above the normal level of the conductive liquid therein, said contact members being in circuit with the other aileron control solenoid and the up-elevator-control solenoid, whereby when the plane is inverted the nrst mentioned circuits are broken and the second mentioned circuits are completed by said conductive liquid whereby the aeroplane is caused to right itself innight.

4. In an aeroplane, a control system including solenoids arranged to activate the controls of the aeroplane, a make and break device comprising a tube of insulating material arranged to ybe mounted on the 4aeroplane and disposed in a vertical position when the plane is in normal night, a body of conductive liquid partially nlling said tube, a lpair of contact members extending into said tube and interposed in the circuit of o ne of the aileron-control solenoids, and of the downelevator-control solenoid, contact members extube above the normal level of the conductive liquid therein, said contact members being in circuit with the other aileron control solenoid and the up-elevator-control solenoid, whereby when the plan`e is inverted the nrst mentioned vcircuits are broken and the second mentionedcircuits are completed by said conductive liquid whereby the aeroplane is caused to right itself in night. and a body of'non-electrolytic fluid in said tube superimposed on the conductive liquid to prevent'iump-sparks between contact members lnot immersed in the conductive liquid.

5. In an aeroplane, a control system including a solenoid arranged to activate the up-elevator of the aeroplane, a make and break device comprising a tube of non-conductive material, a contact member extending into said tube adjacent to one end thereof, a body of conductive liquid contained in said tube and out of contact with said member when the tube is level but coming into contact with said member when the tube is tipped in the proper direction, said liquid being connected with a sourceof electric current whereby when the tube is tipped in the proper'direction said solenoid is energizedA and the up-elevator is activated, analtimeter arranged to signal when the aeroplane descends below a predetermined elevation, and means whereby when said signal is given the tube is tipped to energize said solenoid. 6. In an aeroplane, a control system including a solenoid arranged to activate the up-elevator of the aeroplane, a make and break device'com-` prlsing a tube of non-conductive material. a contact member extending into said tube adjacent to one end thereof, a body of conductive liquid contained in said tube and out of contact with said member when the tube is level but coming into contact with said member when the tube is tipped in the proper direction, said liquid being connected with a 'source of electric current whereby when the tube is tipped in the proper direction said solenoid is energized and the upelevator is activated, a radio frequency altimeter arranged tosignal the descent of the aeroplane below a predetermined elevation, andk means whereby the completion of the signal circuit caues the tube to be tipped to energize said solenoi i 7. In an aeroplane, a control system including a solenoid arranged to activate the up-'elevator of the aeroplane, a make and break device comprising a tube of non-conductive material, a contact member extending into said-tube adjacent to one end thereof, a body of conductive liquid contained in said tube and out of contactwith said member when the tube is level but coming into contact with saidl member when the tube is tipped in the proper direction, said liquid being connected with a'source of electric current whereby when the tube is tipped in the proper direction said solenoid is energized and the up-elevator is ac tlvated, a radio frequency altimeter arranged to signal the descent of the aeroplane below a predetermined elevation, a second solenoid, connections, between the tube and the second solenoid whereby when the second solenoid is energized 1 said tube is tipped and said first solenoid is energized, and electrical connections whereby whenv the signal of the altimeter is given said second solenoid is energized.

8. In means for maintaining an aeroplane in night at a predetermined elevation, the combination of a solenoid having its coil divided into ias sections and arranged to activate the up-elevator I ofthe aeroplane, the degree of activation depending on the number of coil sections which are energized, a make and break device included lin circuit withsaid solenoid and arranged by ybeing tipped to complete the circuit through said coil sections, the extent of such tipping determining the number of coil sections energized, an electrical altimeter, a second solenoid operatively connected to said tube and arranged when energized to tip the tube to energize the first solenoid, the coil of the second solenoid being also divided into sections and the extent to which said tube is tipped depending upon the number oi.' sections of the coil oi' the second solenoid which are energized, and electrical connections including the aitimeter and the second solenoid whereby when the plane descends to various levels below the predetermined elevation of flight the sections of the coil of said second solenoid are enersized.

9. In means for maintaining an aeroplane in ight at a predetermined elevation, the combination of a solenoid having its coil divided into sections and arranged to activate the up-elevator of the aeroplane, the degree of activation depending on the number o! coil sections which are given one section of the second solenoid is energized and when the second .signal is given the entire coil of the second solenoid is energized. JAMES M. HENDRICKSON.

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